Former No. 1 Andy Roddick says 21-year-old Americans Jack Sock and Ryan Harrison must compete with a greater sense of urgency. Sock reached the quarterfinals of Memphis last week, but the world No. 82 fell to Adrian Mannarino in the first round of Delray Beach on Monday. Harrison is currently ranked No. 115 and advanced when Yen-Hsun Lu retired, despite losing the first set.

Roddick has trained with both players.

"There's an upside, but there needs to be a sense of urgency,'' Roddick told the Sun Sentinel. "It's funny, you think you're going to play forever and then you wake up on your 30th birthday and realize you're done. …There's different kinds of pressure that creates motivation. I hope they realize the opportunities they do have."

After his loss to Mannarino, whom he had defeated twice this year at other events, Sock said it was just a bad day at the office.

"Some people can make big jumps right away and then drop off a couple of steps, and you have to work your way back,'' said Sock. "Some people go at a steady pace. In today's game, older people are dominating in their late 20s. It's a process and it's definitely a man's game. There's lots to learn and be gained by being on tour a couple of years. I think I have a pretty good idea what it takes and what I need to do to try to make some big jumps.''